FreePBX poor audio quality fix

I am in need of an experienced freelancer who can fix the poor audio quality issue in my FreePBX phone system. The connection being used is VoIP.

Ideal Skills and Experience:
- Strong knowledge of FreePBX phone system
- Experience in fixing poor audio quality issues in VoIP connections
- Knowledge of various audio codecs and their compatibility with FreePBX
- Excellent problem-solving skills and attention to detail